I used one with DS1. My boys are 18 months apart. I wasn't really a fan. I'm not against them but wouldn't recommend them. My son would just try to pull away the whole time and soon learned how to unhook it. I tried it because he was a runner and he would just unsnap himself from the stroller and get out to run. At 4 he is doing so much better however at 3 we went to disney and he kept trying to run so we made him ride in the ergo to keep him safe.